Affiliation:
1. St. Petersburg State Forestry Engineering University named after S.M. Kirov
Abstract
Abstract—In Pseudotsuga menziesii Mirb. Franco introduced in St. Petersburg, the changes in the apical meristem morphogenesis during the formation of a short bud shoot with covering scales and meristematic primordium of shoot with needles, under the decrease in illumination within the crown were studied. Terminal 1–4-year-old shoots of the third-order branches in the lower part of the crown with a relative light availability (RLA) in the range of 23.9–18.3% perform full annual cycle of morphogenesis of the shoot apical meristem. Before each stage of morphogenesis, the apical meristem performs independent volume growth associated with the formation of mother groups of phytomer cells of covering scales and needles in the peripheral meristem. With RLA reducing to 15.1–15.4%, in terminal 5–6-year-old shoots over the growing season, the apical meristem performs only formation of a short bud shoot with covering scales and stops volume growth. This is because in the vascular bundles of the stele of the short bud stem, the sieve cells of the phloem are not formed, and the xylem part is poorly developed. The direct contact of the apex with the stele of the bud stem is blocked by procambium bundles, since their cells are differentiated and crystalline cellulose is accumulated in the cell walls. The cell walls of the bark parenchyma of the short bud stem contains significantly less birefringent inclusions, and only single small resin receptacles.
Publisher
The Russian Academy of Sciences
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